All Black Tiatia linked to Sunwolves job
Japanese Super Rugby officials told AFP they could not confirm Tiatia's appointment but hoped to make a formal announcement by the end of September.
Englishman Ben Ryan, who led Fiji to gold at the Rio Olympics last month, has also been linked to the Sunwolves job.
Hammett, who has endured a troubled first season with the Sunwolves, will return to New Zealand at the end of the season to take up a role as assistant coach of the Highlanders.
Hammett's appointment by the Sunwolves was one of several to be made alarmingly late, giving the side very little time to prepare for the 2016 campaign.
They hit rock bottom in a 17-92 humiliation by South Africa's Cheetahs in April, prompting criticism from former Japan coach Eddie Jones among others.
The Sunwolves joined the competition following Japan's astonishing performance at last year's World Cup where the Brave Blossoms won three pool games, including a 34-32 shock upset over two-time champions South Africa.
But delays bringing in players and coaching staff sabotaged the team's preparations while Jones, now in charge of England, slammed the Sunwolves' lack of depth as "embarrassing".
Japanese rugby chiefs have made no secret of their desire for the country's top players to turn out for the Sunwolves.
But despite bumper crowds supporting the team, several marquee Japan players snubbed the Sunwolves to sign for other clubs on more lucrative contracts, including Japan captain Michael Leitch and fullback Ayumu Goromaru.
Agence France-Presse